Imaging lens, and electronic apparatus including the same

ABSTRACT

An imaging lens includes first to fifth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant optical parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Application No.201310658569.2, filed on Dec. 9, 2013.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging lens and an electronicapparatus including the same.

2. Description of the Related Art

In recent years, as use of portable electronic devices (e.g., mobilephones and digital cameras) becomes ubiquitous, much effort has been putinto reducing dimensions of portable electronic devices. Moreover, asdimensions of charged coupled device (CCD) and complementary metal-oxidesemiconductor (CMOS) based optical sensors are reduced, dimensions ofimaging lenses for use with the optical sensors must be correspondinglyreduced without significantly compromising optical performance.

U.S. patent application publication no. 20070236811 discloses aconventional imaging lens that includes five lens elements, that has adistortion close to five percent and that has a system length of 12 mm.Such a conventional imaging lens is insufficient to constrain thedistortion and is unsuitable for use in an electronic device thatfocuses on slim size and that may have a thickness of only 10 mm.

Another conventional imaging lens with five lens elements disclosed inU.S. patent application publication no. 20070229984 offers animprovement in image quality and has a system length reduced to 8 mm.However, the size of such a conventional imaging lens is stillunsuitable for current consumer electronic devices.

Reducing the system length of the imaging lens while maintainingsatisfactory optical performance is always a goal in the industry.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an imaginglens having a shorter overall length while maintaining good opticalperformance.

According to one aspect of the present invention, an imaging lenscomprises a first lens element, an aperture stop, a second lens element,a third lens element, a fourth lens element and a fifth lens elementarranged in order from an object side to an image side along an opticalaxis of the imaging lens. Each of the first lens element, the secondlens element, the third lens element, the fourth lens element and thefifth lens element has an object-side surface facing toward the objectside and an image-side surface facing toward the image side.

The object-side surface of the first lens element has a convex portionin a vicinity of a periphery of the first lens element.

The image-side surface of the second lens element has a concave portionin a vicinity of a periphery of the second lens element.

The object-side surface of the third lens element has a convex portionin a vicinity of the optical axis, and the image-side surface of thethird lens element has a concave portion in a vicinity of the opticalaxis.

The object-side surface of the fourth lens element has a concave portionin a vicinity of the optical axis.

The fifth lens element is made of a plastic material, and the image-sidesurface of the fifth lens element has a concave portion in a vicinity ofthe optical axis.

The imaging lens satisfies ALT/T5≦4.7, where T5 represents a thicknessof the fifth lens element at the optical axis, and ALT represents a sumof thicknesses of the first lens element, the second lens element, thethird lens element, the fourth lens element and the fifth lens elementat the optical axis.

The imaging lens does not include any lens element with a refractivepower other than the first lens element, the second lens element, thethird lens element, the fourth lens element and the fifth lens element.

Another object of the present invention is to provide an electronicapparatus having an imaging lens with five lens elements.

According to another aspect of the present invention, an electronicapparatus includes a housing and an imaging module. The imaging moduleis disposed in the housing, and includes the imaging lens of the presentinvention, a barrel on which the imaging lens is disposed, a holder uniton which the barrel is disposed, and an image sensor disposed at theimage side of the imaging lens.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram to illustrate the structure of a lenselement;

FIG. 2 is a schematic diagram that illustrates the first preferredembodiment of an imaging lens according to the present invention;

FIG. 3 shows values of some optical data corresponding to the imaginglens of the first preferred embodiment;

FIG. 4 shows values of some aspherical coefficients corresponding to theimaging lens of the first preferred embodiment;

FIGS. 5( a) to 5(d) show different optical characteristics of theimaging lens of the first preferred embodiment;

FIG. 6 is a schematic diagram that illustrates the second preferredembodiment of an imaging lens according to the present invention;

FIG. 7 shows values of some optical data corresponding to the imaginglens of the second preferred embodiment;

FIG. 8 shows values of some aspherical coefficients corresponding to theimaging lens of the second preferred embodiment;

FIGS. 9( a) to 9(d) show different optical characteristics of theimaging lens of the second preferred embodiment;

FIG. 10 is a schematic diagram that illustrates the third preferredembodiment of an imaging lens according to the present invention;

FIG. 11 shows values of some optical data corresponding to the imaginglens of the third preferred embodiment;

FIG. 12 shows values of some aspherical coefficients corresponding tothe imaging lens of the third preferred embodiment;

FIGS. 13( a) to 13(d) show different optical characteristics of theimaging lens of the third preferred embodiment;

FIG. 14 is a schematic diagram that illustrates the fourth preferredembodiment of an imaging lens according to the present invention;

FIG. 15 shows values of some optical data corresponding to the imaginglens of the fourth preferred embodiment;

FIG. 16 shows values of some aspherical coefficients corresponding tothe imaging lens of the fourth preferred embodiment;

FIGS. 17( a) to 17(d) show different optical characteristics of theimaging lens of the fourth preferred embodiment;

FIG. 18 is a schematic diagram that illustrates the fifth preferredembodiment of an imaging lens according to the present invention;

FIG. 19 shows values of some optical data corresponding to the imaginglens of the fifth preferred embodiment;

FIG. 20 shows values of some aspherical coefficients corresponding tothe imaging lens of the fifth preferred embodiment;

FIGS. 21( a) to 21(d) show different optical characteristics of theimaging lens of the fifth preferred embodiment;

FIG. 22 is a schematic diagram that illustrates the sixth preferredembodiment of an imaging lens according to the present invention;

FIG. 23 shows values of some optical data corresponding to the imaginglens of the sixth preferred embodiment;

FIG. 24 shows values of some aspherical coefficients corresponding tothe imaging lens of the sixth preferred embodiment;

FIGS. 25( a) to 25(d) show different optical characteristics of theimaging lens of the sixth preferred embodiment;

FIG. 26 is a schematic diagram that illustrates the seventh preferredembodiment of an imaging lens according to the present invention;

FIG. 27 shows values of some optical data corresponding to the imaginglens of the seventh preferred embodiment;

FIG. 28 shows values of some aspherical coefficients corresponding tothe imaging lens of the seventh preferred embodiment;

FIGS. 29( a) to 29(d) show different optical characteristics of theimaging lens of the seventh preferred embodiment;

FIG. 30 is a table that lists values of relationships among some lensparameters corresponding to the imaging lenses of the first to seventhpreferred embodiments;

FIG. 31 is a schematic partly sectional view to illustrate a firstexemplary application of the imaging lens of the present invention; and

FIG. 32 is a schematic partly sectional view to illustrate a secondexemplary application of the imaging lens of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

In the following description, “a lens element has a positive (ornegative) refractive power” means the lens element has a positive (ornegative) refractive power in a vicinity of an optical axis thereof. “Anobject-side surface (or image-side surface) has a convex (or concave)portion at a certain area” means that, compared to a radially exteriorarea adjacent to said certain area, said certain area is more convex (orconcave) in a direction parallel to the optical axis. Referring to FIG.1 as an example, the lens element is radially symmetrical with respectto an optical axis (I) thereof. The object-side surface of the lenselement has a convex portion at an area A, a concave portion at an areaB, and a convex portion at an area C. This is because the area A is moreconvex in a direction parallel to the optical axis (I) in comparisonwith a radially exterior area thereof (i.e., area B), the area B is moreconcave in comparison with the area C, and the area C is more convex incomparison with an area E. “In a vicinity of a periphery” refers to anarea around a periphery of a curved surface of the lens element forpassage of imaging light only, which is the area C in FIG. 1. Theimaging light includes a chief ray Lc and a marginal ray Lm. “In avicinity of the optical axis” refers to an area around the optical axisof the curved surface for passage of the imaging light only, which isthe area A in FIG. 1. In addition, the lens element further includes anextending portion E for installation into an optical imaging lensdevice. Ideally, the imaging light does not pass through the extendingportion E. The structure and shape of the extending portion E are notlimited herein. In the following embodiments, the extending portion E isnot depicted in the drawings for the sake of clarity.

Referring to FIG. 2, the first preferred embodiment of an imaging lens10 according to the present invention includes a first lens element 3,an aperture stop 2, a second lens element 4, a third lens element 5, afourth lens element 6, a fifth lens element 7, and an optical filter 8arranged in the given order along an optical axis (I) from an objectside to an image side. The optical filter 8 is an infrared cut filterfor selectively absorbing infrared light to thereby reduce imperfectionof images formed at an image plane 9. However, in some embodiments, theoptical filter 8 may be a visible light filter that only allows passageof infrared light for use in an infrared detector.

Each of the first, second, third, fourth and fifth lens elements 3-7 andthe optical filter 8 has an object-side surface 31, 41, 51, 61, 71, 81facing toward the object side, and an image-side surface 32, 42, 52, 62,72, 82 facing toward the image side. Light entering the imaging lens 10travels through the object-side and image-side surfaces 31, 32 of thefirst lens element 3, the aperture stop 2, the object-side andimage-side surfaces 41, 42 of the second lens element 4, the object-sideand image-side surfaces 51, 52 of the third lens element 5, theobject-side and image-side surfaces 61, 62 of the fourth lens element 6,the object-side and image-side surfaces 71, 72 of the fifth lens element7, and the object-side and image-side surfaces 81, 82 of the opticalfilter 8, in the given order, to form an image on the image plane 9.Each of the object-side surfaces 31, 41, 51, 61, 71 and the image-sidesurfaces 32, 42, 52, 62, 72 is aspherical and has a center pointcoinciding with the optical axis (I).

The lens elements 3-7 are made of a plastic material in this embodiment,and at least one of the lens elements 3-6 may be made of other materialsin other embodiments. In addition, each of the lens elements 3-7 has arefractive power.

In the first preferred embodiment, which is depicted in FIG. 2, thefirst lens element 3 has a positive refractive power. The object-sidesurface 31 of the first lens element 3 has a convex portion 311 in avicinity of the optical axis (I), and a convex portion 312 in a vicinityof a periphery of the first lens element 3. The image-side surface 32 ofthe first lens element 3 has a concave portion 321 in a vicinity of theoptical axis (I), and a convex portion 322 in a vicinity of theperiphery of the first lens element 3.

The second lens element 4 has a negative refractive power. Theobject-side surface 41 of the second lens element 4 has a concaveportion 411 in a vicinity of the optical axis (I), and a convex portion412 in a vicinity of a periphery of the second lens element 4. Theimage-side surface 42 of the second lens element 4 has a concave portion421 in a vicinity of the optical axis (I), and a concave portion 422 ina vicinity of the periphery of the second lens element 4.

The third lens element 5 has a positive refractive power. Theobject-side surface 51 of the third lens element 5 has a convex portion511 in a vicinity of the optical axis (I), and a concave portion 512 ina vicinity of a periphery of the third lens element 5. The image-sidesurface 52 of the third lens element 5 has a concave portion 521 in avicinity of the optical axis (I), and a convex portion 522 in a vicinityof the periphery of the third lens element 5.

The fourth lens element 6 has a positive refractive power. Theobject-side surface 61 of the fourth lens element 6 has a concaveportion 611 in a vicinity of the optical axis (I), and a concave portion612 in a vicinity of a periphery of the fourth lens element 6. Theimage-side surface 62 of the fourth lens element 6 is a convex surface.

The fifth lens element 7 has a negative refractive power. Theobject-side surface 71 of the fifth lens element 7 has a convex portion711 in a vicinity of the optical axis (I), and a concave portion 712 ina vicinity of a periphery of the fifth lens element 7. The image-sidesurface 72 of the fifth lens element 7 has a concave portion 721 in avicinity of the optical axis (I), and a convex portion 722 in a vicinityof the periphery of the fifth lens element 7.

The imaging lens 10 satisfies ALT/T5≦4.7, where T5 represents athickness of the fifth lens element 7 at the optical axis (I), and ALTrepresents a sum of thicknesses of the first lens element 3, the secondlens element 4, the third lens element 5, the fourth lens element 6 andthe fifth lens element 7 at the optical axis (I). Since the fifth lenselement 7 has an optical effective diameter greater than that of each ofthe lens elements 3-6, reduction in T5 is relatively difficult. Thus,when T5 has been determined, smaller ALT/T5 refers to smaller ALT, whichcontributes to reduction in the overall system length. When thisrelationship is satisfied, optical performance is still relatively goodeven with the reduced system length.

In the first preferred embodiment, the imaging lens 10 does not includeany lens element with refractive power other than the aforesaid lenselements 3-7.

Shown in FIG. 3 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the first preferredembodiment. The imaging lens 10 has an overall system effective focallength (EFL) of 4.109 mm, a half field-of-view (HFOV) of 36.136°, anF-number of 2.08, and a system length of 4.929 mm. The system lengthrefers to a distance between the object-side surface 31 of the firstlens element 3 and the image plane 9 at the optical axis (I).

In this embodiment, each of the object-side surfaces 31-71 and theimage-side surfaces 32-72 is aspherical, and satisfies the relationshipof

$\begin{matrix}{{Z(Y)} = {{\frac{Y^{3}}{R}/\left( {1 + \sqrt{1 - {\left( {1 + K} \right)\frac{Y^{3}}{R^{2}}}}} \right)} + {\sum\limits_{i = 1}^{n}{a_{i} \times Y^{i}}}}} & (1)\end{matrix}$

where:

R represents a radius of curvature of an aspherical surface;

Z represents a depth of the aspherical surface, which is defined as aperpendicular distance between an arbitrary point on the asphericalsurface that is spaced apart from the optical axis (I) by a distance Y,and a tangent plane at a vertex of the aspherical surface at the opticalaxis (I);

Y represents a perpendicular distance between the arbitrary point on theaspherical surface and the optical axis (I);

K represents a conic constant; and

a_(i) represents an i^(th) aspherical coefficient.

Shown in FIG. 4 is a table that lists values of some asphericalparameters of the aforementioned relationship (1) corresponding to thefirst preferred embodiment.

Relationships among some of the lens parameters corresponding to thefirst preferred embodiment are as follows:

TTL=4.929; ALT=2.525; Gaa=1.008;

TTL/G45=45.636; TTL/T2=18.956;

Gaa/T1=1.575; ALT/G45=23.380;

ALT/Gaa=2.505; Gaa/T3=2.400;

ALT/G34=4.208; Gaa/G23=5.929;

Gaa/G34=1.680; TTL/T4=7.886;

TTL/Gaa=4.890; TTL/ALT=1.952;

and ALT/T1=3.945,

where:

T1 represents a thickness of the first lens element 3 at the opticalaxis (I);

T2 represents a thickness of the second lens element 4 at the opticalaxis (I);

T3 represents a thickness of the third lens element 5 at the opticalaxis (I);

T4 represents a thickness of the fourth lens element 6 at the opticalaxis (I);

G23 represents an air gap length between the second lens element 4 andthe third lens element 5 at the optical axis (I);

G34 represents an air gap length between the third lens element 5 andthe fourth lens element 6 at the optical axis (I);

G45 represents an air gap length between the fourth lens element 6 andthe fifth lens element 7 at the optical axis (I); Gaa represents a sumof four air gap lengths among the first lens element 3, the second lenselement 4, the third lens element 5, the fourth lens element 6 and thefifth lens element 7 at the optical axis (I);

ALT represents a sum of thicknesses of the lens elements 3-7 at theoptical axis (I); and

TTL represents a distance at the optical axis (I) between theobject-side surface 31 of the first lens element 3 and the image plane 9at the image side.

FIGS. 5( a) to 5(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefirst preferred embodiment. In each of the simulation results, curvescorresponding respectively to wavelengths of 470 nm, 555 nm, and 650 nmare shown.

It can be understood from FIG. 5( a) that, since each of the curvescorresponding to longitudinal spherical aberration has a focal length ateach field of view (indicated by the vertical axis) that falls withinthe range of ±0.03 mm, the first preferred embodiment is able to achievea relatively low spherical aberration at each of the wavelengths.Furthermore, since the curves at each field of view are close to eachother, the first preferred embodiment has a relatively low chromaticaberration.

It can be understood from FIGS. 5( b) and 5(c) that, since each of thecurves falls within the range of ±0.2 mm of focal length, the firstpreferred embodiment has a relatively low optical aberration.

Moreover, as shown in FIG. 5( d), since each of the curves correspondingto distortion aberration falls within the range of ±2%, the firstpreferred embodiment is able to meet requirements in imaging quality ofmost optical systems.

In view of the above, even with the system length reduced down to 4.929mm, the imaging lens 10 of the first preferred embodiment is still ableto achieve a relatively good optical performance.

Referring to FIG. 6, the differences between the first and secondpreferred embodiments of the imaging lens 10 of this invention reside inthat: the image-side surface 62 of the fourth lens element 6 has aconcave portion 621 in a vicinity of a periphery of the fourth lenselement 6.

Shown in FIG. 7 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the second preferredembodiment. The imaging lens 10 has an overall system focal length of4.014 mm, an HFOV of 36.777°, an F-number of 2.038, and a system lengthof 4.949 mm.

Shown in FIG. 8 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thesecond preferred embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the second preferred embodiment are as follows:

TTL=4.949; ALT=2.480; Gaa=0.835;

TTL/G45=41.244; TTL/T2=23.568;

Gaa/T1=1.305; ALT/G45=20.667;

ALT/Gaa=2.970; Gaa/T3=2.088;

ALT/G34=5.976; Gaa/G23=4.912;

Gaa/G34=2.012; TTL/T4=7.614;

TTL/Gaa=5.927; TTL/ALT=1.996;

and ALT/T1=3.875.

FIGS. 9( a) to 9(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesecond preferred embodiment. It can be understood from FIGS. 9( a) to9(d) that the second preferred embodiment is able to achieve arelatively good optical performance.

Referring to FIG. 10, the differences between the first and thirdpreferred embodiments of the imaging lens 10 of this invention reside inthat: the image-side surface 62 of the fourth lens element 6 has aconcave portion 621 in a vicinity of a periphery of the fourth lenselement 6.

Shown in FIG. 11 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the third preferredembodiment. The imaging lens 10 has an overall system focal length of4.003 mm, an HFOV of 36.85°, an F-number of 2.038, and a system lengthof 4.856 mm.

Shown in FIG. 12 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thethird preferred embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the third preferred embodiment are as follows:

TTL=4.856; ALT=2.275; Gaa=1.095;

TTL/G45=16.186; TTL/T2=24.279;

Gaa/T1=1.825; ALT/G45=7.583;

ALT/Gaa=2.078; Gaa/T3=3.000;

ALT/G34=4.740; Gaa/G23=6.441;

Gaa/G34=2.281; TTL/T4=7.832;

TTL/Gaa=4.435; TTL/ALT=2.134;

and ALT/T1=3.792.

FIGS. 13( a) to 13(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thethird preferred embodiment. It can be understood from FIGS. 13( a) to13(d) that the third preferred embodiment is able to achieve arelatively good optical performance.

Referring to FIG. 14, the differences between the first and fourthpreferred embodiments of the imaging lens 10 of this invention reside inthat: the image-side surface 62 of the fourth lens element 6 has aconcave portion 621 in a vicinity of a periphery of the fourth lenselement 6.

Shown in FIG. 15 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the fourth preferredembodiment. The imaging lens 10 has an overall system focal length of4.016 mm, an HFOV of 36.761°, an F-number of 2.018, and a system lengthof 4.976 mm.

Shown in FIG. 16 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefourth preferred embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the fourth preferred embodiment are as follows:

TTL=4.976; ALT=2.610; Gaa=0.860;

TTL/G45=41.464; TTL/T2=23.694;

Gaa/T1=1.265; ALT/G45=21.750;

ALT/Gaa=3.035; Gaa/T3=1.755;

ALT/G34=5.932; Gaa/G23=5.059;

Gaa/G34=1.955; TTL/T4=7.655;

TTL/Gaa=5.786; TTL/ALT=1.906;

and ALT/T1=3.838.

FIGS. 17( a) to 17(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefourth preferred embodiment. It can be understood from FIGS. 17( a) to17(d) that the fourth preferred embodiment is able to achieve arelatively good optical performance.

Referring to FIG. 18, the differences between the first and fifthpreferred embodiments of the imaging lens 10 of this invention reside inthat: the image-side surface 62 of the fourth lens element 6 has aconcave portion 621 in a vicinity of a periphery of the fourth lenselement 6.

Shown in FIG. 19 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the fifth preferredembodiment. The imaging lens 10 has an overall system focal length of4.086 mm, an HFOV of 36.285°, an F-number of 2.055, and a system lengthof 5.007 mm.

Shown in FIG. 20 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefifth preferred embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the fifth preferred embodiment are as follows:

TTL=5.007; ALT=2.610; Gaa=1.295;

TTL/G45=11.380; TTL/T2=25.036;

Gaa/T1=2.272; ALT/G45=5.932;

ALT/Gaa=2.015; Gaa/T3=2.943;

ALT/G34=4.833; Gaa/G23=7.618;

Gaa/G34=2.398; TTL/T4=7.153;

TTL/Gaa=3.867; TTL/ALT=1.918;

and ALT/T1=4.579.

FIGS. 21( a) to 21(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefifth preferred embodiment. It can be understood from FIGS. 21( a) to21(d) that the fifth preferred embodiment is able to achieve arelatively good optical performance.

FIG. 22 illustrates the sixth preferred embodiment of an imaging lens 10according to the present invention, which has a configuration similar tothat of the first preferred embodiment.

Shown in FIG. 23 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the sixth preferredembodiment. The imaging lens 10 has an overall system focal length of3.804 mm, an HFOV of 38.28°, an F-number of 1.933, and a system lengthof 4.513 mm.

Shown in FIG. 24 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thesixth preferred embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the sixth preferred embodiment are as follows:

TTL=4.513; ALT=2.346; Gaa=1.124;

TTL/G45=17.719; TTL/T2=18.777;

Gaa/T1=1.826; ALT/G45=9.210;

ALT/Gaa=2.087; Gaa/T3=2.981;

ALT/G34=3.971; Gaa/G23=6.501;

Gaa/G34=1.903; TTL/T4=7.581;

TTL/Gaa=4.015; TTL/ALT=1.924;

and ALT/T1=3.810.

FIGS. 25( a) to 25(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesixth preferred embodiment. It can be understood from FIGS. 25( a) to25(d) that the sixth preferred embodiment is able to achieve arelatively good optical performance.

Referring to FIG. 26, the differences between the first and seventhpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 51 of the third lens element 5 has aconvex portion 511 in a vicinity of the optical axis (I) and a convexportion 513 in a vicinity of a periphery of the third lens element 5.

Shown in FIG. 27 is a table that lists values of some optical datacorresponding to the surfaces 31-81, 32-82 of the seventh preferredembodiment. The imaging lens 10 has an overall system focal length of3.734 mm, an HFOV of 38.461°, an F-number of 1.949, and a system lengthof 4.630 mm.

Shown in FIG. 28 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to theseventh preferred embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the seventh preferred embodiment are as follows:

TTL=4.630; ALT=2.409; Gaa=1.196;

TTL/G45=15.143; TTL/T2=18.285;

Gaa/T1=2.235; ALT/G45=7.879;

ALT/Gaa=2.015; Gaa/T3=2.758;

ALT/G34=4.171; Gaa/G23=6.208;

Gaa/G34=2.070; TTL/T4=6.876;

TTL/Gaa=3.873; TTL/ALT=1.922;

and ALT/T1=4.503.

FIGS. 29( a) to 29(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of theseventh preferred embodiment. It can be understood from FIGS. 29( a) to29(d) that the seventh preferred embodiment is able to achieve arelatively good optical performance.

Shown in FIG. 30 is a table that lists the aforesaid relationships amongsome of the aforementioned lens parameters corresponding to the sevenpreferred embodiments for comparison. It should be noted that the valuesof the lens parameters and the relationships listed in FIG. 30 arerounded off to the third decimal place. When each of the lens parametersof the imaging lens 10 according to this invention satisfies thefollowing optical relationships, the optical performance is stillrelatively good even with the reduced system length:

(1) TTL/G45≦46.0: In comparison with TTL, G45 has a relatively smallreducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 10.0≦TTL/G45≦46.0.

(2) TTL/T2≦19.0: In comparison with TTL, T2 has a relatively smallreducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 17.0≦TTL/T2≦19.0.

(3) Gaa/T1≦2.3: In general, since the first lens element 3 is providedwith the positive refractive power, the first lens element 3 isrelatively thick and the reducible ratio of T1 is relatively small. WhenGaa/T1 is smaller than 2.3, reduction of Gaa is relatively large, sothat the overall system length of the imaging lens 10 may be reduced.Better optical quality may be achieved when this relationship issatisfied. Preferably, 1.0≦Gaa/T1≦2.3.

(4) ALT/G45≦26.0: In comparison with ALT, G45 has a relatively smallreducible ratio so that an appropriate distance may be maintainedbetween the fourth lens element 6 and the fifth lens element 7 toenhance image quality. Preferably, 5.0≦ALT/G45≦26.0.

(5) ALT/Gaa≧2.0: In comparison with ALT, Gaa has a relatively largereducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 2.0≦ALT/Gaa≦4.0.

(6) Gaa/T3≦3.0: In comparison with Gaa, T3 has a relatively smallreducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 1.0≦Gaa/T3≦3.0.

(7) ALT/G34≦6.0: In comparison with ALT, G34 has a relatively smallreducible ratio so that an appropriate distance may be maintainedbetween the third lens element 5 and the fourth lens element 6 toenhance image quality. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 3.0≦ALT/G34≦6.0.

(8) Gaa/G23≦6.0: In comparison with Gaa, G23 has a relatively smallreducible ratio so that an appropriate distance may be maintainedbetween the second lens element 4 and the third lens element 5 toenhance image quality. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 4.0≦Gaa/G23≦6.0.

(9) Gaa/G34≦2.5: In comparison with Gaa, G34 has a relatively smallreducible ratio so that an appropriate distance may be maintainedbetween the third lens element 5 and the fourth lens element 6 toenhance image quality. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 1.0≦Gaa/G34≦2.5.

(10) TTL/T4≦8.0: In comparison with TTL, T4 has a relatively smallreducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 6.0≦TTL/T4≦8.0.

(11) TTL/Gaa≧4.0: In comparison with TTL, Gaa has a relatively largereducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 4.0≦TTL/Gaa≦7.0.

(12) TTL/ALT≧1.8: In comparison with TTL, ALT has a relatively largereducible ratio. In consideration of optical properties andmanufacturing ability, better arrangement may be achieved when thisrelationship is satisfied. Preferably, 1.8≦TTL/ALT≦3.0.

(13) ALT/T1≦4.0: In general, since the first lens element 3 is providedwith the positive refractive power, the first lens element 3 isrelatively thick and the reducible ratio of T1 is relatively small. WhenALT/T1 is smaller than 4.0, reduction of ALT is relatively large, sothat the overall system length of the imaging lens 10 may be reduced.Better optical quality may be achieved when this relationship issatisfied. Preferably, 3.0≦ALT/T1≦4.0.

To sum up, effects and advantages of the imaging lens 10 according tothe present invention are described hereinafter.

For each of the seven preferred embodiments of this invention, thelongitudinal spherical, astigmatism and distortion aberrationsrespectively fall within the range of ±0.03 mm, the range of ±0.2 mm andthe range of ±2%. The off-axis rays corresponding respectively towavelengths of 470 nm (blue ray), 555 nm (green ray), and 650 nm (redray) are around the imaging point. It is evident from the deviationrange of each of the curves that deviations of the imaging points of theoff-axis rays with different heights are well controlled so that theimaging lens 10 has good performance in terms of spherical aberration,astigmatism aberration and distortion aberration at each of thewavelengths. Furthermore, since the curves with different wavelengthsthat respectively represent red, green, and blue rays are close to eachother, the imaging lens 10 has a relatively low chromatic aberration. Asa result, by virtue of the abovementioned design of the lens elements,good image quality may be achieved.

In addition, in each of the aforesaid seven preferred embodiments, thesystem length of this invention is smaller than 5.1 mm. As a result, notonly can this invention have good optical performance, but the systemlength of this invention can also be shortened to achieve a goal ofminiaturization.

Shown in FIG. 31 is a first exemplary application of the imaging lens10, in which the imaging lens 10 is disposed in a housing 11 of anelectronic apparatus 1 (such as a mobile phone, but not limitedthereto), and forms a part of an imaging module 12 of the electronicapparatus 1.

The imaging module 12 includes a barrel 21 on which the imaging lens 10is disposed, a holder unit 120 on which the barrel 21 is disposed, andan image sensor 130 disposed at the image plane 9 (see FIG. 2).

The holder unit 120 includes a first holder portion 121 in which thebarrel 21 is disposed, and a second holder portion 122 having a portioninterposed between the first holder portion 121 and the image sensor130. The barrel 21 and the first holder portion 121 of the holder unit120 extend along an axis (II), which coincides with the optical axis (I)of the imaging lens 10.

Shown in FIG. 32 is a second exemplary application of the imaging lens10. The differences between the first and second exemplary applicationsreside in that, in the second exemplary application, the holder unit 120is configured as a voice-coil motor (VCM), and the first holder portion121 includes an inner section 123 in which the barrel 21 is disposed, anouter section 124 that surrounds the inner section 123, a coil 125 thatis interposed between the inner and outer sections 123, 124, and amagnetic component 126 that is disposed between an outer side of thecoil 125 and an inner side of the outer section 124.

The inner section 123 and the barrel 21, together with the imaging lens10 therein, are movable with respect to the image sensor 130 along anaxis (III), which coincides with the optical axis (I) of the imaginglens 10. The optical filter 8 of the imaging lens 10 is disposed at thesecond holder portion 122, which is disposed to abut against the outersection 124. Configuration and arrangement of other components of theelectronic apparatus 1 in the second exemplary application are identicalto those in the first exemplary application, and hence will not bedescribed hereinafter for the sake of brevity.

By virtue of the imaging lens 10 of the present invention, theelectronic apparatus 1 in each of the exemplary applications may beconfigured to have a relatively reduced overall thickness with goodoptical and imaging performance, so as to reduce cost of materials, andsatisfy requirements of product miniaturization.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. An imaging lens comprising a first lens element,an aperture stop, a second lens element, a third lens element, a fourthlens element and a fifth lens element arranged in order from an objectside to an image side along an optical axis of said imaging lens, eachof said first lens element, said second lens element, said third lenselement, said fourth lens element and said fifth lens element having anobject-side surface facing toward the object side, and an image-sidesurface facing toward the image side, wherein: said object-side surfaceof said first lens element has a convex portion in a vicinity of aperiphery of said first lens element; said image-side surface of saidsecond lens element has a concave portion in a vicinity of a peripheryof said second lens element; said object-side surface of said third lenselement has a convex portion in a vicinity of the optical axis, and saidimage-side surface of said third lens element has a concave portion in avicinity of the optical axis; said object-side surface of said fourthlens element has a concave portion in a vicinity of the optical axis;said fifth lens element is made of a plastic material, and saidimage-side surface of said fifth lens element has a concave portion in avicinity of the optical axis; said imaging lens satisfies ALT/T5≦4.7,where T5 represents a thickness of said fifth lens element at theoptical axis, and ALT represents a sum of thicknesses of said first lenselement, said second lens element, said third lens element, said fourthlens element and said fifth lens element at the optical axis; and saidimaging lens does not include any lens element with a refractive powerother than said first lens element, said second lens element, said thirdlens element, said fourth lens element and said fifth lens element. 2.The imaging lens as claimed in claim 1, further satisfying TTL/G45≦46.0,where TTL represents a distance at the optical axis between saidobject-side surface of said first lens element and an image plane at theimage side, and G45 represents an air gap length between said fourthlens element and said fifth lens element at the optical axis.
 3. Theimaging lens as claimed in claim 2, further satisfying TTL/T2≦19.0,where T2 represents the thickness of said second lens element at theoptical axis.
 4. The imaging lens as claimed in claim 3, furthersatisfying Gaa/T1≦2.3, where Gaa represents a sum of four air gaplengths among said first lens element, said second lens element, saidthird lens element, said fourth lens element and said fifth lens elementat the optical axis, and T1 represents the thickness of said first lenselement at the optical axis.
 5. The imaging lens as claimed in claim 1,further satisfying ALT/G45≦26.0, where G45 represents an air gap lengthbetween said fourth lens element and said fifth lens element at theoptical axis.
 6. The imaging lens as claimed in claim 1, furthersatisfying ALT/Gaa≧2.0, where Gaa represents a sum of four air gaplengths among said first lens element, said second lens element, saidthird lens element, said fourth lens element and said fifth lenselements at the optical axis.
 7. The imaging lens as claimed in claim 1,further satisfying Gaa/T3≦3.0, where Gaa represents a sum of four airgap lengths among said first lens element, said second lens element,said third lens element, said fourth lens element and said fifth lenselements at the optical axis, and T3 represents the thickness of saidthird lens element at the optical axis.
 8. The imaging lens as claimedin claim 7, further satisfying ALT/G34≦6.0, where G34 represents the airgap length between said third lens element and said fourth lens elementat the optical axis.
 9. The imaging lens as claimed in claim 1, furthersatisfying Gaa/G23≦6.0, where Gaa represents a sum of four air gaplengths among said first lens element, said second lens element, saidthird lens element, said fourth lens element and said fifth lenselements at the optical axis, and G23 represents the air gap lengthbetween said second lens element and said third lens element at theoptical axis.
 10. The imaging lens as claimed in claim 9, furthersatisfying Gaa/G34≦2.5, where G34 represents the air gap length betweensaid third lens element and said fourth lens element at the opticalaxis.
 11. The imaging lens as claimed in claim 1, further satisfyingTTL/T4≦8.0, where TTL represents a distance at the optical axis betweensaid object-side surface of said first lens element and an image planeat the image side, and T4 represents the thickness of said fourth lenselement at the optical axis.
 12. The imaging lens as claimed in claim11, further satisfying TTL/Gaa≧4.0, where Gaa represents a sum of fourair gap lengths among said first lens element, said second lens element,said third lens element, said fourth lens element and said fifth lenselements at the optical axis.
 13. The imaging lens as claimed in claim1, further satisfying TTL/ALT≧1.8, where TTL represents a distance atthe optical axis between said object-side surface of said first lenselement and an image plane at the image side.
 14. The imaging lens asclaimed in claim 13, further satisfying TTL/T4≦8.0, where T4 representsthe thickness of said fourth lens element at the optical axis.
 15. Theimaging lens as claimed in claim 14, further satisfying ALT/T1≦4.0,where T1 represents the thickness of said first lens element at theoptical axis.
 16. An electronic apparatus comprising: a housing; and animaging module disposed in said housing, and including an imaging lensas claimed in claim 1, a barrel on which said imaging lens is disposed,a holder unit on which said barrel is disposed, and an image sensordisposed at the image side of said imaging lens.